Temporal proximity is a basic and crucial cue to determine whether different sensory inputs belong to a single object or event. To integrate auditory and visual signals into a unified percept, the paired stimuli should be presented close in time and fall within a limited time window known as the Temporal Binding Window (TBW). The width of the TBW, a proxy of audiovisual temporal integration ability, has been found to correlate with higher-order cognitive and social functions.
Autism spectrum disorder (ASD) and schizophrenia spectrum disorders are two typical neurodevelopmental disorders that share overlapping features. They both exhibit impaired audiovisual temporal integration, manifesting as abnormally widened TBW, contributing to the corresponding aberrant perceptual experiences and social communicative difficulties. However, little is known regarding the similarities and differences between autism spectrum disorder and schizophrenia spectrum disorders in the underlying mechanisms of abnormal temporal integration.
Dr. Raymond Chan's team from the Institute of Psychology of the Chinese Academy of Sciences (CAS) and his collaborators have conducted two related studies to examine the audiovisual temporal processing ability between children and adolescents with early-onset schizophrenia and high functioning autism respectively.
They recruited 31 adolescents with early-onset schizophrenia and 30 healthy controls in Study 1, whereas 31 children with ASD and 32 healthy controls in Study 2 . All participants in both studies were requested to complete the Temporal Order Judgement Tasks within visual and auditory modalities, the Audiovisual Simultaneity Judgement Tasks for both non-speech and speech stimuli, and an eye-tracking task with fluent speech videos.
Results showed that reduced temporal acuity was a generalized impairment in patients with early-onset schizophrenia, affecting unisensory and multisensory modalities, as well as non-speech and speech stimuli. In contrast, individuals with autism only exhibited widened audiovisual TBW for speech stimuli, with their unisensory temporal acuity and the TBW for non-speech stimuli largely preserved.
Applying the eye-tracking task with ecologically-valid linguistic stimuli, both groups of patients exhibited reduced sensitivity of detecting audiovisual speech asynchrony and impaired visual attention to synchronous speakers. Moreover, difficulties in audiovisual speech integration could contribute to social dysfunctions.
Taken together, these findings demonstrate both shared and distinct patterns of atypical temporal processing in these two clinical samples. This study deepens our understanding of the relationship between autism spectrum disorder and schizophrenia spectrum disorders from a perspective of multisensory integration and may implicate the potential effect of temporal sensory training on clinical populations.
Dr. Chan's team has recently developed a perceptual and cognitive training programme and is now undertaking a study to examine whether these altered audiovisual temporal processing and corresponding clinical symptoms and cognitive function could be improved.
The study is now available online on Clinical Psychological Science in a paper entitled "Audiovisual temporal processing in children and adolescents with schizophrenia and autism: Evidence from simultaneity judgement tasks and eye-tracking data."
It was supported by a grant form the National Science Foundation of China and the CAS Key Laboratory of Mental Health of the Institute of Psychology.
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